Industrial catalytic converters are used for example to convert sulphur dioxide gas to sulphur trioxide gas in the manufacture of sulphuric acid. Large pressure vessels of stainless steel have multiple layers of granular catalyst housed within the converters and gas is passed through the permeable granular catalyst beds under pressure and at elevated temperatures. Due to the highly corrosive nature of the gases, all ducting and support structures within the converter are constructed of stainless steel. Such structures are expensive to build due to the relatively high cost of materials, the complexity of welding stainless steel to maintain corrosion resistance, and the requirement of highly skilled labour often working in remote locations.
Examples of prior art converters are shown in U.S. Pat. No. 4,335,076 to McFarland and U.S. Pat. No. 5,232,670 to Cameron. Earlier converters included vertically stacked flat support platforms within a cylindrical converter vessel, having a grillage supported on columns. Since all internal components had to be corrosion resistant, construction of such grillage platforms was very expensive and led to curved plate supports as described in the above mentioned patents. From such examples it will be appreciated that converters are highly variable in configuration with external and internal gas ducts, plenums and catalyst support platforms and heat exchangers combined to form a complex, large scale and expensive structure.
When high cost materials and highly skilled workers are necessary, adoption of an efficient practical converter design can multiply the savings of the owner not only in the capital cost of construction, the reduced land area occupied but also in the reduction of air flow drag losses through ducts and reduction in routine maintenance. Especially in remote locations, simple savings in the weight of components can significantly reduce shipping costs, and simplification of the design can reduce the total cost of skilled labour on site and in prefabrication. In manufacturing and erection the repetition of standard or identical components aids in simplifying procedures and reduces costs through economies of scale. Symmetry in the design of repetitive components results in simplified components that are less costly to manufacture and erect. In most instances symmetry of design reduces local stress concentrations that usually arise due to geometric inconsistencies, and therefore can lead to a reduction in the amount of material used since stresses are reduced in local areas of a structure.
The opposite is also true that failure to fully consider the lifecycle costs of designing, manufacturing, construction and operation of a complex converter design can increase overall costs significantly.
Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below.